


Sweet Truth

by Raikishi



Series: The Lie in You [2]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - Soulmates, Anal Sex, Bottom Dimitri Alexandre Blaiddyd, Explicit Sexual Content, M/M, Plot What Plot/Porn Without Plot, Porn with Feelings, Public Sex, Soulmates, Teacher-Student Relationship
Language: English
Status: Completed
Published: 2020-08-17
Updated: 2020-08-17
Packaged: 2021-03-05 23:40:06
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,282
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25953859
Author URL: https://archiveofourown.org/users/Raikishi/pseuds/Raikishi
Summary: “Are you certain?” Dimitri asks and it sounds like a plead, softly spoken as if he did not dare to make the request. He bites his lip and in a smaller voice, “Soulmates cannot lie to each other …”Soulmate.Was that what this was?There’s an unfamiliar roar in Byleth’s pulse, something heady and potent as if he’d taken a swig of too-strong mead. His head swims as Dimitri leans in. Helplessly, Byleth finds his attention caught on the low flush on Dimitri’s cheeks. On the faint tremble to the mouth that, only seconds ago, had been pressed to his –“So… Professor, if you don’t mind me asking,” Dimitri says, his body thrumming with a desperation Byleth cannot help but respond to, “Do you not want me, my … my mate?”Byleth enjoys his newfound soulmateM!Dimileth day 1
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth
Series: The Lie in You [2]
Series URL: https://archiveofourown.org/series/1999264
Comments: 8
Kudos: 158





	Sweet Truth

**Author's Note:**

  * Inspired by [The Sweetest Lie](https://archiveofourown.org/works/25532548) by [Raikishi](https://archiveofourown.org/users/Raikishi/pseuds/Raikishi). 



> This is the porny fix it for my last angsty soulmate AU 
> 
> Dimitri can have his soulmate in this timeline. As a treat.
> 
> The two pieces have divergent pieces and are not linked.

“Ha – _Professor!_ ” the groan tears from Dimitri’s chest, guttural and deep and far too loud given where they are.

Byleth slaps a hand over Dimitri’s mouth, gripping tighter when the prince moans at the touch. Byleth casts a glance around them, crowding them further into the shadows behind Byleth’s room until they are mostly hidden by the shrubbery and stack of boxes below the window. 

He curses himself for his foolishness. They had made it, fumbling and clumsy with stolen kisses and quick gropes, all the way from the knight’s hall. Yet, somehow, had fallen short of their destination. Dimitri had leaned in and whispered something in Byleth’s ear, something pitched low and sweet and so full of desperate desire, Byleth - fool that he was - had been unable to resist pressing Dimitri into the rough brick.

Dimitri had moaned at the shove and gone eagerly. Blaiddyd’s strength had only drawn Byleth closer instead of shoved him aside, had ground their hips together until Byleth had withdrawn a little vial from his pouch and worked two fingers into the prince who’d pleaded and whined until – 

Byleth frowns down at the scant space between their bodies. Shudders.

Fuck - what the hell had Dimitri said?

Byleth squints at the prince but there’s no trace of malice, not even the faintest smear of a scheming thought. No, that was more Claude’s place and Dimitri –

Dimitri looks like he has little else on his mind besides trying to steal another kiss. His eyes are dark, full of uncommon greed as he pecks at the corners of Byleth’s mouth. One gauntleted hand holds Byleth’s wrist, tucking the hand firmly against Dimitri’s throat as the prince steals another eager kiss. It’s a quick fluttering thing, light on Byleth’s mouth and it makes him tingle. So carefully delicate, Byleth wants to – 

“Professor –!” Dimitri whimpers around a particularly hard thrust, moaning louder when Byleth shushes him again.

“Shh,” Byleth breathes against his mouth and presses a finger to his lips when the proximity only makes Dimitri moan, “Dimitri, be quiet for me. Please?”

“Anything you ask,” Dimitri pants and Byleth nearly shakes apart at the bright adoration in those eyes. 

The readiness in them stirs a new heat in Byleth’s stomach, a sweet heady curl of pleasure that trembles at the base of his spine. He works his hips faster as if this were only a tavern fuck in the back alleys. Some quick stolen moment before Jeralt came looking for him –

Dimitri shudders full-bodied, head tilting back against the brick. It exposes the long clean line of his throat and he holds both hands to his mouth to silence a wail when Byleth drives in again at the same angle. The prince shivers, desperation dripping off him as he tries to hike his legs higher, and tugs at the pants around his knees as if trying to wrestle them lower. 

Byleth chokes off a swear as Dimitri clenches down all around him and the prince latches onto the noise like a bloodhound. 

“Did you like that, Professor?” giddily spoken and full of that same bright eagerness Dimitri brought to all their training sessions.

_“Would you allow me to test something new?”_

“Would you allow me to do it again?”

Byleth shakes his head, biting his lip to keep the truth from spilling from his mouth. Dimitri squeezes down again on the next thrust, flexes carefully as he hikes his hips, clenching all around Byleth’s cock in a way that has Byleth hiding a moan in the prince’s throat.

“Do you like that? Professor, you must tell me – please, I know you cannot lie to me,” Dimitri begs and his entire face goes flush with delight at his own words. 

The same eager happiness that’d made his eyes shine and the tension of his jaw soften in the knight’s hall when he’d pressed up against Byleth’s mouth with a careful kiss. Byleth had not stopped him. Had been unable to. 

_“I don’t want –“ Byleth touches a hand to his mouth, wondering at the word that does not fall. He tries again, “I don’t want –“_

_Again it falls away from him._

_He’d never struggled with words no matter what the mercenaries believed. He’d only been quiet as a child because he’d felt no need to offer anything more than curt phrases and simple words._

_“This,” he says just to try the word alone and it comes out with ease. Again, he tries to offer his excuse, “I don’t want –“_

_And it dies in his mouth._

_Dimitri seizes his arm, eyes shining with a desperate hope that makes Byleth’s chest ache._

_“Are you certain?” Dimitri asks and it sounds like a plead, softly spoken as if he did not dare to make the request. He bites his lip and in a smaller voice, “Soulmates cannot lie to each other …”_

_Soulmate._

_Was that what this was?_

_There’s an unfamiliar roar in Byleth’s pulse, something heady and potent as if he’d taken a swig of too-strong mead. His head swims as Dimitri leans in. Helplessly, Byleth finds his attention caught on the low flush on Dimitri’s cheeks. On the faint tremble to the mouth that, only seconds ago, had been pressed to his –_

_“So… Professor, if you don’t mind me asking,” Dimitri says, his body thrumming with a desperation Byleth cannot help but respond to, “Do you not want me, my … my mate?”_

_“I do,” the words drop like stones before Byleth can stop them._

_“Oh,” Byleth breathes out over Dimitri’s happy gasp, realization striking like a thunderclap._

_Byleth remembers too many free days spent at the knight hall. He’d always be looking for a new quest or a whetstone. Each time, without fail, he would forget when Dimitri appeared. Byleth recalls still more moments at the training grounds, lingering behind, uncommonly slow at cleaning his weapons. Recalls the little jolt of pleasure each time Dimitri would appear, requesting yet another spar before bed._

_“I do want you,” Byleth says working out the words slowly, trembling a little as they leave him._

_Dimitri beams at him. It’s beautiful and brilliant. For a long moment, Byleth cannot help but think he wants no one else but himself to see this._

“I want to please you,” Dimitri moans now in Byleth’s ear and the earnest truth makes Byleth burn. Dimitri’s mouth sets in an adorably determined pout as he swivels his hips and bears down, providing a delicious drag that rips the moan from Byleth’s mouth.

“Oh, my mate,” Dimitri whimpers in response, his blue eyes shining and adoring, “I think I love pleasing you. Will you show me how? It can – _oh,_ it would be yet another thing for you to teach me, _Professor_.”

This man was going to be the death of him.

“Dimitri,” Byleth gasps in his ear, unable to stop his hips from driving forward, from slapping a rough hold on Dimitri’s pale thighs and sinking a bruise into the skin as he fucks him into the brickwork until the prince is moaning anew, unstoppable and – _fuck –_

“Shhh, Dimitri – “ Byleth begs, digging his teeth into Dimitri’s throat, “Dima, you have to be quiet.”

Dimitri shudders in his grasp and does not obey. For all his rigid adherence to school rules and careful attention in the classroom, he seems intent on disobeying Byleth’s orders here and now.

“Call me - _oh_ , call me that again,” Dimitri says, the end of his words breaking off into a groan Byleth licks out of his mouth, surrendering them readily to Byleth’s tongue, “Ooh, I’ve dreamed of this. My mate calling me –“

He sinks his teeth into Byleth’s shoulder, entire body twitching when someone’s door opens. A flicker of candlelight lights the paved path leading to the dormitories and a voice lifts up to their left. Byleth utters a near inaudible swear, ignoring the scandalized look Dimitri flashes him - oh, so it would be rough language that shocked him but not public fornication – and crowds them both closer to the wall, pressing deeper into the shadows and subsequently sinking his cock deeper into Dimitri who writhes at the new fullness and smothers a wail into Byleth’s shoulder.

“Jeez, Lysithea just fess up and say you don’t want to go to the sauna because of ghosts,” Leonie says and there’s the sound of a scuffle.

“I am _not_ frightened!” Lysithea says.

“Oh, really now – oh Goddess!”

“What?! What is it!!”

Byleth leans forward, hiding Dimitri’s face as the two turn the corner, heartbeat roaring his ears. He can feel the prince trembling harder, his expression hidden in Byleth’s cloak. The arm of Byleth’s jacket frays at the shoulders, fabric tearing beneath Blaiddyd’s strength. Dimitri squirms, smothered pants growing more and more frantic. 

A glyph lights the air and Dimitri clenches down so hard Byleth’s thoughts burn out in fire for a long terrifying second. When he comes back, Dimitri’s mouth is working a silent plead into Byleth’s chest and Lysithea’s Miasma has spun into the air well far away from them.

“Oy, don’t go throwing that around – it was a joke – “

“Why you juvenile, ill-mannered –“

“Hey, I’m here doing _you_ a favor, let’s not go swinging insults –“

“Ugh!” 

“Hey, wait up, aren’t you afraid of the ol’ boogeyman –?”

Dimitri twists in Byleth’s shoulder as they pass, moving his face out of Byleth’s cloak just enough to leave the impression he is watching the girls walk away. For his part, Byleth holds rigid and still until the footsteps clamor up the stairs to the sauna. Until Leonie’s laugh echoes over them and covers the wet drag as Byleth starts to pull out –

“You –“ Byleth swears, unable to help the buck of his hips, cock throbbing as he spies the messy wetness on Dimitri’s uniform and lower belly, “You came?”

“Yes,” Dimitri slaps a hand over his mouth, embarrassment shining through on the dark rose of his cheeks, his thighs twitching on either side of Byleth’s hips.

“I – I don’t – what pushed you over?” Byleth doesn’t mean the words as a question but Dimitri’s hand spasms and his eyes round out, looking so much like a hunted doe Byleth cannot help himself, “Dimitri, we were nearly caught…”

“Yes,” the words exit on thin gasp and Byleth –

Byleth had never considered himself a man with greedy desires until today. Never wanted to bat around prey until they whined and begged beneath him. Slowly, he licks his lips, his blood roaring when he sees Dimitri track the motion. 

“Did you. ... did you want to be caught?” Byleth asks, batting aside Dimitri’s hand and seizing his jaw in a rough grip when the prince shakes his head. Byleth rocks experimentally, twisting his hips until the prince pants and then slides two fingers into his mouth, holding him open. Dimitri’s tongue tracks over the fingertips then knuckles, laving eagerly in the divot between the two digits. 

Byleth wonders if he’d work that hard on a cock and shudders, pressing down on Dimitri’s tongue, darkly satisfied when the prince moans for it. Byleth traces the line of his teeth, drifting over the rough scrape of his tongue, as if able to steal the truth from Dimitri’s mouth. 

Well … 

Byleth pauses.

That he _could_ do. 

He grinds into Dimitri at an angle, cock throbbing as the realization strikes him, adrenaline a heady burn in his mind, shot straight to the core of him as with any potent Kingdom vodka.

“Dimitri, did you get off on the thought of being seen like this?” Byleth asks again and the prince grimaces, moaning around Byleth’s fingers, shaking his head desperately even as the truth flies from his tongue.

“ _Yes,_ ” the word is mangled around Byleth’s knuckles but clear enough.

Blue eyes widen, filling with guilt and shame, humiliation dragging the blush on Dimitri’s cheeks lower into the disheveled collar of his shirt front.

“Why?” Byleth asks, unable to help himself, delighting in Dimitri’s choked cry as he smothers the reply. 

“Professor,” Dimitri gasps desperately, “Please don’t ask.”

“ _Why?_ ” Byleth repeats and then when Dimitri squeezes his eyes shut and only suckles on his fingers, removes them to hold Dimitri’s hips.

The prince sobs when Byleth pulls out, resisting mightily. Dimitri’s legs tighten around the small of Byleth’s back and he squeezes down as if intent on coaxing Byleth into staying. He doesn’t manage but it’s a damn near thing. Byleth shivers as he rests the crown of his cock against Dimitri’s opening, resisting the increasingly urgent tugs and only rocking against the sharp cut of Dimitri’s hipbone – oh, that was nice. He could work himself to completion just here –

Byleth shudders at the thought of leaving the prince like this, unsatisfied and wailing for it. His pants and hips stained with mixed seed, painted just like a back alley fuck –

Dimitri hates it, fighting like an alley cat as he claws at Byleth’s shirtfront. 

His hips twitch, trying to grind back against Byleth. He’s half-hard again already - stamina due to his crest or simply a feature of the same Dimitri who could spend days at the training ground - Byleth doesn’t question it, too entranced by the near frantic way Dimitri tries to drag him back inside. 

“Tell me why like a good _boy_ and I might consider fucking you again,” Byleth says on a low purr, his teeth closing roughly over Dimitri’s ear for a sharp yank. 

Shocked betrayal twists Dimitri’s face and he gapes at Byleth for a long moment, stunned into silence, the dark of his eyes swallowing up the blue as he shivers, a little whimper dropping from his mouth and –

Oh –

Who would have thought the respectable prince of Faerghus was so inclined. 

Dimitri ducks away from Byleth’s knowing smirk, his cheeks ablaze and burning hot as he hides in Byleth’s neck. Byleth wonders if he knows his cock is twitching, stirred by such a simple promise. He holds back from pointing it out, stopped by Dimitri’s soft reply.

“I liked the thought of being claimed,” Dimitri confesses on a low sob, and then when Byleth doesn’t immediately reward him - too stunned stupid by the admission - pulls his face out of Byleth’s neck to kiss a plead against Byleth’s mouth, “My mate … I told you. Don’t be cruel _–ah!”_

_Cruel…_

Byleth wonders at the accusation as he fucks back into his mate, set aflame by the delicious way Dimitri melts beneath him.

The mercenaries had all been convinced of the wickedness lent by Byleth’s demon monicker but he’d never thought himself _cruel_ –

Here and now …

He fists his hand over Dimitri’s cock and the thick blurt of hungry pleasure that burns through his gut at Dimitri’s answering whimper makes him tighten his fist. Makes him want to bite. Torment. Toy with his lovely _soulmate_ until the prince could think of no one else and turn those beautiful pleading eyes to no one else but –

“Prof – _Byleth!_ ” Dimitri’s teeth dig into Byleth’s shoulder at the next thrust, entire body drawn tight as a bowstring, the pleasure dripping off his tongue like the richest honeyed mead. 

His entire body unravels before Byleth. A royal body lent out to mercenary – 

Byleth shivers, biting down hard on a nipple, eliciting a sharp pained gasp. For a half-second, he thinks to apologize but Dimitri arches into the pain with a gasping wail, and a new blurt of slick leaks from the tip of his cock. Dimitri touches a hand to the reddening skin, eyes wide with wonderment as he pries at it cautiously, a whining gasp hanging on his lips as he pokes at the mark. He moans when Byleth tears the shirt from his shoulders, husking encouraging whimpers as Byleth sinks more marks beneath the collar of his shirt and down his chest. 

_Wanting to be claimed._

“ _Ah_ – !” Dimitri cringes as Byleth pinches one the forming bruises, body drawing tight and perfect – 

“I don't think anyone would mistake you as anything other than mine now,” Byleth remarks, twisting one of the bruises hard - ruthlessly –

Dimitri comes on only that, arching his head to the heavens as he shoves his fist against his mouth, smothering a sharp bitten off cry, as he shoots, thick and messy over Byleth’s fingers, staining his pants and Byleth’s cloak, entire body shaking as –

With a growl, Byleth grips Dimitri’s hip with a hand, burying himself deep, chasing after his own orgasm, fucking into him with sharp quick thrusts. His hand grips Dimitri’s cock, wringing out the last of the prince’s orgasm and does not stop even when Dimitri starts to shake and tremble. 

“Byleth,” Dimitri begs on a low wail, entire body twitching as over-sensitivity chases away the all-encompassing relief of orgasm. Byleth only tightens his grip, chasing him down when the prince cringes away. Beneath the gasping pleads, Byleth has the distinct sense that Dimitri would have allowed him to do anything he so desired given the dazed dreamy look in his eyes and faint smile on that pretty mouth. 

"Dima," Byleth purrs over his claim, thrusting so hard Dimitri jerks with the motion. 

“Yes, yes,” comes the sweet reply, “ _My mate_ , please … finish inside me.”

Byleth drowns himself in the eagerness, drinking in the moans and whimpers, hoarding them all like a dragon of legend. His skin burns as if he’d called the Crest over himself and with a few near brutal thrusts, he empties himself into a surrendering body, slamming his mouth to Dimitri’s and knocking them both against the brick. He rocks hard, grinding against Dimitri’s hips hard in a blind chase for his own pleasure, grinding until the lightning race of pleasure through his body settles as a low weight over him. 

With a shuddering gasp, he pulls back just enough to track biting kisses against Dimitri’s slack mouth until the prince starts to respond. They stay for a long moment, lost in the feel of one another. 

A cat yowls from somewhere beyond them followed by someone’s, “Shut up!”

With a sigh, Byleth pulls himself away, cracking his jaw as he pulls out, grimacing at the wetness staining Dimitri’s thighs and the ground beneath them. He swears under his breath as he tries to clean them up the best he can, huffing a little when the prince offers no help. Dimitri aims for his mouth each time Byleth hovers too closer, stealing kisses and offering nothing but a distraction until Byleth gives up.

“Maybe the baths for both of us,” Byleth says, “Come, you can borrow some of my clothes.”

The prince blinks and looks down at himself, flushing deep as if he was only just now aware of what a picture he made. Byleth looks away quickly when he sees Dimitri poking at the fingerprint bruises on his hip, pulse roaring at the sight. 

“Ah - um, sorry –“

“Don’t be,” Dimitri reply is sharp. Hungry. Like he’s already – 

Byleth shudders, struck dizzy by the renewed desire in Dimitri’s face.

“Professor,” Dimitri says under his breath and the title alone sounds dirtier than anything from the mouth of prostitutes. A frisson of pleasure tracks up Byleth’s spine and Byleth recalls faintly, it really hadn’t been anything terribly vulgar Dimitri had said on the way from the knight’s hall.

Dimitri had only leaned in close, lips brushing against Byleth’s mouth just inches from Byleth’s door and only offered an innocent question –

_“Professor, will you be gentle with me?”_

“Professor, can we go to the baths after another…?”

In that same soft wondering voice as if he could not believe he was in Byleth’s arms, wearing that same bright besotted gaze and Byleth –

“Oh,” Byleth cracks out, the full truth of his words shaking the air between them, “I’d do anything you ask.”


End file.
